Harmony Design & Development builds custom ADUs across the San Francisco Bay Area, including detached units, garage conversions, and in-law suites. They manage permits, design, and construction from start to finish.
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Based in Napa and serving St. Helena, Calistoga, and our neighbors in Sonoma, Solano, and Green Valley, we’re a full-service ADU builder with the experience to navigate local codes, streamline approvals, and deliver exceptional results. Our in-house team of designers, builders, and project managers ensures seamless communication, consistent quality, and on-time, on-budget completion.
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Quality Choice Construction & Painting offers ADU construction services including studio, 1-bedroom, and 2-bedroom units. Options include garage conversions, backyard cottages, and detached ADUs for rental income or multi-generational living.
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Golden State ADUs is a Sacramento-based full-service ADU contractor offering design, permitting & construction. With 10+ years experience and 100+ projects, they build detached ADUs, in-law suites & backyard cottages across California.
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Nestadu is a full-service ADU builder offering custom site-built and prefab accessory dwelling units. Prefab models range from $115K–$317K. Custom builds start at $400/sq ft. Financing options include HELOCs, construction loans, and CA grants.
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New Avenue, Inc is a full-service design-build company serving the San Francisco Bay Area and Portland, OR since 2011. They specialize in ADUs, custom homes, renovations, additions, and Enclaves, managing design, permitting, and construction under one roof.
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Mills Builders Inc is a Sacramento-based residential construction firm founded in 1999. Specializing in ADU construction, home renovation, in-fill development, and whole-house builds, they serve Sacramento's historic neighborhoods with decades of hands-on expertise.
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Northbay Home Solutions offers full-service ADU construction in San Rafael, San Francisco & North Bay. Services include detached ADUs, garage conversions & JADUs, covering design, permits & build.
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Edri Construction, Inc. is a Walnut Creek-based ADU contractor serving the Bay Area. They specialize in garage conversions, detached ADUs, attached additions, in-law suites, and JADUs, handling design, permitting, and project management.
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Shed Shop offers ADUs (Accessory Dwelling Units) via their Mini Cottage program. Sizes range from 192 to 480 sq. ft. Services include foundation, plumbing, electrical, permits & more. Available in select cities.
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We are a family-first, boutique residential design & build firm serving the Orinda and East Bay community. We’re not just service providers — we’re your neighbors. We understand the local permitting process, the hillside terrain, the fire-hazard restrictions, and the thoughtful planning needed to create homes that truly work for East Bay families.
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prefabADU is a Bay Area ADU builder with 16+ years of experience offering affordable kits and plans from under $45K. With 12 state-approved plans valid across California, they simplify permits, design, and installation for homeowners.
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ADUs add rental income & property value. Services include garage conversions, detached ADUs, JADUs & granny flats. ADU Feasibility Studies cover code, utilities & ROI. Architectural services via Adapt Dwellings ensure smooth approval to construction.
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Eagle ADU is a licensed ADU builder in Northern California offering three signature models: Eagle Studio ($180K–$220K), Eagle One ($230K–$280K), and Eagle Two ($310K–$360K), with rental income potential up to $4,000/month.
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Licensed ADU contractor Full Steam Ahead Construction serves East Bay homeowners with custom accessory dwelling units, including garage conversions, backyard cottages & in-law suites. Serving Concord, Oakland, Berkeley & more.
read moreNapa, California, is world-renowned for its stunning vineyards, Mediterranean climate, and high property values. These characteristics make Accessory Dwelling Units (ADUs) an especially attractive investment for homeowners in the area. With median home prices well above the California average, adding an ADU in Napa can significantly increase property value and generate substantial rental income — particularly given the city's thriving tourism industry and consistent demand for short-term and long-term housing.
Working with experienced ADU contractors in Napa, CA is essential because local regulations can be complex. The City of Napa follows California state ADU laws while also enforcing its own municipal codes. Key considerations include:
Hiring a local ADU contractor familiar with Napa's specific permitting process can save homeowners significant time and money. The City of Napa's Building Division oversees permit applications, and experienced contractors understand how to navigate this process efficiently. A knowledgeable contractor will also be aware of Napa's utility connection requirements, including water and sewer hookup fees, which can be a notable cost factor in ADU projects.
Napa homeowners typically pursue several types of ADU construction, depending on their lot size and goals:
When selecting an ADU contractor in Napa, California, homeowners should verify that the contractor holds a valid California Contractors State License Board (CSLB) license, carries proper insurance, and has demonstrated experience with local Napa County and City of Napa building codes. Request references from past ADU projects in the area and ensure your contractor provides a detailed written contract covering timelines, costs, and permit responsibilities. A well-built ADU in Napa is not just a home improvement — it's a smart long-term investment in one of California's most desirable communities.